2004 mercury/yamaha 115 4-stroke not starting/running if cold. Intermittent Issue

[mercaha 115]

• I will give a little back story on this post and what I have done to get where I am now.
  
  Bought this motor used approximately 1 year ago and have replaced several mechanical components as well as electrical/sensor components throughout the time that I have owned it.
  
  As of recent, I am having an intermittent issue with the motor not starting/running while cold. If it does start it will idle just fine until throttle is applied.
  
  IF out of water and on muffs, I can "cold start" it and if I bump the throttle, it will start to fluctuate in RPMs and eventually die. On the same token, I can unplug the voltage regulator, and the motor will jump back to the 900-1200 idle range and run smoothly. It will do this until the motor has reached optimal running temperature (or so it seems).
  
  IF it is in the water, I can get it to start and it will idle just fine. Once I go to get on the plain, the motor hiccups and immediately shuts off. Same thing again, I simply unplug the voltage regulator until the motor gets warm (roughly 10-20 minutes depending on water temp) and it runs fine the rest of the day.
  
  I have also cranked it in the morning before leaving to go fishing and drove all the way to the ramp, and motor would not start AT ALL.
  
  Luckily, I have several tools on hand at all times and was able to check a few things. When this occurred, first thing I tried was some starting fluid. The motor did not even try to start, so I immediately thought spark plugs. So I removed all the spark plugs, which evidently had some decent carbon build up. So I went to the auto parts store and replaced all 4. Next, I checked the spark and surprisingly enough it seemed that the spark looked a little weak. After some research, I figured it was either the coil packs or the stator. After testing the coil packs per the manufactures service manual, everything seemed fine. So then I thought back to having to unplug the voltage regulator to get the motor to warm up. So next, I replaced the stator and voltage regulator. This resulted in nothing but a waste of money, motor was still having the intermittent issue.
  
  Next, I checked a couple of sensors and tested them per the service manual. TPS was perfect. IAC valve was working just fine.
  
  Then I was onto the fuel side of the motor. I have now replaced the high pressure fuel pump (located in the VST), the lift pump, fuel lines, filters, and water separator.... nothing. Fuel pressure is right where it needs to be during both priming and running.
  
  Next, I checked continuity from the computer to all the sensors/ electrical components around the motor, everything was fine. Cleaned all the ground around the motor. Nothing.
  
  I am now looking into the thermosensor the starboard side of the motor, hoping it could be the ticket winner for this intermittent issue.
  
  Please if anybody has ever seen a similar issue, let me know, I do not know what the next step would be.
  
  Just to recap replaced parts
  - Fuel pump
  - Lift pump
  - fuel lines
  - fuel filters
  - voltage regulator
  - stator
  - throttle position sensor
  - spark plugs
  - thermosensor (this week)